This invention relates to the use of acid-hydrolyzable esters comprising compounds having two alkyl groups bearing pendant ester groups, aliphatic groups, or acyl groups, or mixtures thereof, linked together by means of an acid labile linkage of the formula, EQU --O--(C(CH.sub.3).sub.p H.sub.2-p)--O--
where p=0 to 2,
as edible, preferably partially digestible, fat mimetics suitable for use in neutral or alkaline food compositions.
Dietary fat is the most concentrated source of energy of all the nutrients, supplying 9 kcal/gram, about double that contributed by either carbohydrate or protein. The amount of fat in the American diet has increased in the last 60 years by about 25% (Mead, J., et al. Lipids, Plenum, N.Y., 1986, page 459), so that fats now provide approximately 40% (or more) of the daily caloric intake. Moreover, technological advances in the food industry, including efficient and safe hydrogenation procedures, have changed the kind of fat in foods.
Because fats are high in calories and because certain fats appear to pose a health risk when consumed in large quantities over time, a number of national advisory committees on nutrition have made recommendations differing in detail, but the common theme is a reduction in the total amount of fat in the diet (Gottenbos, J. J., chapter 8 in Beare-Rogers, J., ed., Dietary Fat Requirements in Health and Development, A.O.C.S. 1988, page 109). Yet fat contributes to the palatability and flavor of food, since most food flavors are fat-soluble, and to the satiety value, since fatty foods remain in the stomach for longer periods of time than do foods containing protein and carbohydrate. Furthermore, fat is a carrier of the fat-soluble vitamins, A, D, E, and K, and the essential fatty acids, which have been shown to be important in growth and in the maintenance of many body functions. Hence, major research efforts have focused on ways to produce food substances that provide the same functional and organoleptic properties as fats, but not the calories.
A number of fat replacements have heretofore been suggested (recently reviewed by Hamm, D. J., 49 J. Food Sci. 419 (1984), Haumann, B. J., 63 J. Amer. Oil Chem. Soc. 278 (1986) and LaBarge, R. G., 42 Food Tech. 84 (1988)). Hamm divides replacement fats into two broad categories: structurally reengineered triglycerides modified to retain their conventional functional properties in foods, while removing their susceptibility toward hydrolysis or subsequent absorption during digestion, and materials developed from chemistry unrelated to triglycerides.
Examples of the former class of triglyceride analogues include compounds having the glycerol moiety replaced with alternate polyols (e.g., pentaerythritol in U.S. Pat. No. 2,962,419 to Minich, or sugars in U.S. Pat. No. 3,600,186 to Mattson and Volpenhein and U.S. Pat. No. 4,840,815 to Meyer, et al.); compounds having the fatty acids replaced with alternate acids (e.g., branched esters as described in U.S. Pat. No. 3,579,548 to Whyte); compounds having insertions between the glycerol and the fatty acid (e.g., ethoxy or propoxy groups in U.S. Pat. No. 4,861,613 to White and Pollard); compounds having reversed esters (e.g., malonates in U.S. Pat. No. 4,482,927 to Fulcher, trialkoxytricarballylates in U.S. Pat. No. 4,508,746 to Hamm and carboxy/carboxylates in U.S. Pat. No. 4,830,787 to Klemann and Finley); and compounds having the ester bonds replaced by ether bonds (Can. Pat. No. 1,106,681 to Trost).
Examples of the latter category of fat replacements chemically unrelated to triglycerides are mineral oil (suggested as early as 1894 in U.S. Pat. No. 519,980 to Winter); polyglucose and polymaltose (U.S. Pat. No. 3,876,794 to Rennhard); jojoba wax (W. Ger. Pat. No. 3,529,564 to Anika); polyoxyalkylene esters (U.S. Pat. No. 4,849,242 to Kershner); polyvinyl alcohol esters (U.S. Pat. No. 4,915,974 to D,Amelia and Jacklin), and polysiloxane (Eur. Pat. Ap. No. 205,273 to Frye).
Nondigestible or nonabsorbable edible fat replacements have proved disappointing when tested in feeding trials, where gastrointestinal side effects occurred, in some cases so extreme that frank anal leakage was observed. Nondigestible fats appear to act as a laxative and are expelled from the body, eliciting foreign body reactions like those early documented for mineral oil (Stryker, W. A., 31 Arch. Path. 670 (1941), more recently summarized in Goodman and Gilman's Pharmacological Basis of Therapeutics, 7th ed., Macmillan Pub. Co., N.Y. 1985, pp. 1002-1003). In the U.S.D.A.,s assessment of the caloric availability and digestibility of a series of new-type fats in the 1960's (e.g., amylose fatty acid esters, diglyceride esters of succinic, fumaric, and adipic acids, and polymeric fats from stearic, oleic and short-chain dibasic acids; see Booth, A. N., and Gros, A. T., 40 J. Amer. Oil Chem. Soc. 551 (1963) and the references cited therein), rats fed the experimental fats exhibited undesirable gastrointestinal side effects similar to what had already been observed with mineral oil consumption by people. In several of the balance studies, the diarrhea was so extreme that digestibility coefficients could not be calculated in the trial feedings (ibid., Table I, p. 552).
Polyglycerol and polyglycerol esters, suggested as fat replacements by Babayan and Lehman (U.S. Pat. No. 3,637,774), have been suggested for use as fecal softening agents as well (U.S. Pat. No. 3,495,010 to Fossel). A number of remedies have been recommended to combat the anal leakage observed when sucrose polyesters are ingested (e.g., employing cocoa but ters, U.S. Pat. No. 4,005,195 to Jandacek, incorporating saturated fatty groups, Eur. Pat. Ap. No. 233,856 to Bernhardt, or mixing residues, U.S. Pat. No. 4,797,300 to Jandacek, et al.), and dietary fiber preparations have been incorporated into polysaccharide and/or polyol-containing foodstuffs to help inhibit the diarrheal effect (U.S. Pat. No. 4,304,768 to Staub et aI.). Partially digestible fat replacements have also been suggested (U.S. Pat. No. 4,830,787 to Klemann and Finley; U.S. Pat. No. 4,849,242, cited above; and U.S. Pat. No. 4,927,659 to Klemann, et al.).